Project Abstract This application for an NIA Administrative Supplement proposes to expand the Alzheimer's Disease Risk and Ethnic Factors: The Case of Arab Americans (R01AG057510) study by measuring genome-wide genotypes and incorporating alleles of the Apolipoprotein E gene (APOE). The study is the first of its kind to focus on AD health disparities in Arab Americans (N=600) aged 65 and over living in the metro-Detroit area, home to the largest and most visible Arab American community in the US. We propose to extend our health disparities research by collecting genome-wide genotype data using the Illumina Infinium Global Screening Array-24 v1.0 (GSA) BeadChip. Further, we plan to compare and contrast the frequency of APOE-?4 to representative samples of non-Arab whites and blacks from the same geographic area. By expanding our project to include genetic data, we will be uniquely positioned to address the following aims: 1) Characterize genome-wide genotypes, including APOE genotypes, among older Arab Americans, whites and blacks from the same geographic area; 2) Determine whether differences in cognition, MCI and AD across older Arab Americans, whites and blacks is independent of APOE genotype; 3) Test for effect modification by race/ethnicity of the link between APOE genotype and cognitive health. This administrative supplement will fund the collection of currently-unavailable genotype data for a newly visible population in comparative perspective. Adding genetic measures to our pioneering study of social and behavioral factors in AD among Arab Americans, whites and blacks provides an innovative, cost effective opportunity to more fully identify health disparities, with special insights into the interplay between gene and social factors. The addition of genetics will substantially contribute to the comprehensive battery of cognitive and functional health thus permitting significant refinement of theory about AD risk in this growing and high-cost disease.